Page 3
STEP 2 – REFRIGERANT PIPING
IMPORTANT
If this unit is being matched with an approved line set
or indoor unit coil that was previously charged with
mineral oil, or if it is being matched with a coil which
was manufactured before January of 1999, the coil and
line set must be ushed prior to installation. Take care to
empty all existing traps. Polyol ester (POE) oils are used
in Lennox units charged with HFC-410A refrigerant.
Residual mineral oil can act as an insulator, preventing
proper heat transfer. It can also clog the expansion
device and reduce system performance and capacity.
Failure to properly ush the system per this instruction
and the detailed Installation and Service Procedures
manual will void the warranty.
Flush the existing line set per the following instructions.
For more information, refer to the Installation and Service
Procedures manual available on LennoxPros.com. CAU-
TION - DO NOT attempt to ush and re-use existing line
sets or indoor coil when the system contains contaminants
(i.e., compressor burn out).
If a new line set is being installed, size the piping per table 1.
TABLE 1
REFRIGERANT LINE SET – INCHES (MM)
Model
Valve Field
Connections
Recommended Line Set
Liquid
Line
Vapor
Line
Liquid
Line
Vapor
Line
L15 Line Sets
-018
3/8 in.
(10 mm)
3/4 in.
(19 mm)
3/8 in.
(10 mm)
3/4 in.
(19 mm)
L15-41
15 ft. - 50 ft.
(4.6 m - 15 m)
-024
-030
-036
3/8 in.
(10 mm)
7/8 in.
(22 mm)
3/8 in.
(10 mm)
7/8 in.
(22 mm)
L15-65
15 ft. - 50 ft.
(4.6 m - 15 m)
-042
-048
-060
3/8 in.
(10 mm)
1-1/8 in.
(28 mm)
3/8 in.
(10 mm)
1-1/8 in.
(28 mm)
Field Fabricated
NOTE - Some applications may require a eld-provided 7/8" to
1-1/8" adapter.
NOTE - When installing refrigerant lines longer than 50
feet, refer to the Refrigerant Piping Design and Fabrica-
tion Guidelines manual available on LennoxPros.com
(Corp. 9351-L9), or contact the Technical Support Depart-
ment Product Application group for assistance.
NOTE - For new or replacement line set installation, refer
to Service and Application Note - Corp. 9112-L4 (C-91-4).
WARNING
When using a high pressure gas such as
nitrogen to pressurize a refrigeration or air
conditioning system, use a regulator that can
control the pressure down to 1 or 2 psig (6.9
to 13.8 kPa).
WARNING
Refrigerant can be harmful if it is inhaled. Refrigerant
must be used and recovered responsibly.
Failure to follow this warning may result in personal
injury or death.
WARNING
Fire, Explosion and Personal Safety hazard.
Failure to follow this warning could result in
damage, personal injury or death.
Never use oxygen to pressurize or purge
refrigeration lines. Oxygen, when exposed
to a spark or open ame, can cause re and/
or an explosion, that could result in property
damage, personal injury or death.
WARNING
Polyol ester (POE) oils used with HFC-410A refrigerant
absorb moisture very quickly. It is very important that the
refrigerant system be kept closed as much as possible.
DO NOT remove line set caps or service valve stub caps
until you are ready to make connections.
IMPORTANT
Some scroll compressors have an internal vacuum
protector that will unload scrolls when suction pressure
goes below 20 psig. A hissing sound will be heard when
the compressor is running unloaded. Protector will reset
when low pressure in system is raised above 40 psig.
DO NOT REPLACE COMPRESSOR.
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